The question to Arthur B Culvahouse Jr was one he would have heard dozens of times since arriving in Australia a couple of months ago as Donald Trump's appointee: How do you play the role of official representative of the most controversial US President ever?

Five long seconds ticked by on the ABC News Breakfast set as the ambassador thought carefully about his answer.

"With gratitude," he eventually declared, before pointing out, in perhaps one of the greatest understatements of the year, that it was indeed an interesting time to be in the type of job he now holds.

"What I tell people is: look at our policies, look at the results. And don't pay attention to the background noise," he said.

When asked to confirm whether he was referring to the President's tweets in his comment about background noise, Mr Culvahouse Jr said: "The tweets."

It was a quintessentially diplomatic response for a man whose task it is to keep the relationship between Australia and the US on an even keel when the established norms no longer seem to apply.

It could, in fact, be a career-defining challenge for a man who has built an impressive resume as the consummate Washington insider.

In the 1970s, Mr Culvahouse Jr worked for famed Republican senator Howard Baker, before serving a stint as White House adviser to former US president Ronald Reagan.

He was also in charge of finding vice-presidential candidates for Donald Trump and John McCain ("Sarah Palin will probably be on my epitaph," he joked).

In recent years Mr Culvahouse Jr, 70, had been happily back in the private sector, working as the chairman of an elite Washington law firm — until he received a phone call out of the blue.

"It was a surprise," he said.

"I was minding my own business in August and Vice-President Pence and then Jared Kushner, the President's son-in-law, and Secretary [of State Mike] Pompeo all called and said that we need an ambassador to Australia, and we want you to consider it.

"I had never been to Canberra, so I came over to Canberra and did a little diligence.

"I went to the War Memorial. I met with some retired officials and was smitten, frankly, and I'm honoured to be here," he said.

Tweets 'are part of President's style'

Now that he's installed in Canberra, the quietly-spoken ambassador has some candid advice for Australians still adapting to Donald Trump's unconventional communication strategy.

Mr Culvahouse Jr said there would be ups and downs with China, but he was confident a more balanced trading relationship would be the end result.

He was also keen to stress the US was Australia's largest economic partner (in terms of direct investment and employment) and that was something he was very keen to build on during his time in Canberra.

He also foreshadowed more joint military exercises involving the Darwin-based US Marines.

'President Trump is a disrupter'

For the most part, the US-Australia relationship will happily tick on.

I've lost count of the number of American officials who've told me since 2016 that the alliance will continue regardless of who is sitting in the Oval Office.

Donald Trump's Twitter problem

Last week Donald Trump met with Twitter's chief executive to reportedly vent about losing followers. But that isn't the figure the President should really be worrying about.

The big question is whether the current occupant has changed the nature of the US presidency for good.

On this one, the ambassador has a much more assured response.

"I think what we're seeing is the self-correcting genius of the American republic," he said.

"We had too much conventional wisdom. It was operating to the detriment of large segments of the US society.

"They wanted a disrupter. President Trump is a disrupter.

"He's upset conventional wisdom, and I think probably in the future the pendulum will sweep back the other way."